Sulfur is often a contaminant in hydrocarbons and in materials derived from hydrocarbons. Sulfur compounds such as hydrogen sulfide, as well as mercaptans, thiols, and other organosulfur compounds can present a problem with subsequent use of such materials since, in addition to being pollutants, they are chemically reactive and can poison catalysts and corrode a variety of equipment. In a number of applications, fuel cells are run on a feedstock material comprising a reformate derived from a hydrocarbon material such as JP8 fuel. This reformate is a hydrogen rich fuel stream which will also include sulfur materials derived from the hydrocarbon source. As noted, such sulfur materials can be very detrimental to fuel cell catalysts and membranes. Therefore, the prior art has implemented a number of approaches to providing methods and materials for removing sulfur contaminants from feedstock materials. In typical prior art approaches, metal oxide compounds such as iron oxide, zinc oxide, and the like have been used to scavenge hydrogen sulfide and other compounds from feedstock materials. In other instances, elemental iron has been used as a sorbent material in guard beds for protecting catalysts from trace sulfur impurities. Such materials are disclosed, for example, in a publication entitled “Review of Mid- to High-Temperature Sulfur Sorbents for Desulfurization of Biomass- and Coal-derived Syngas” Energy Fuels DOI: 10.1021/ef9007149 (Jul. 11, 2009). Problems have been encountered in the use of prior art materials since, in some instances, the chemical kinetics of the sulfidation of the absorbent material are unduly slow. Furthermore, it is desirable that any sulfur absorbent material be capable of being easily regenerated for reuse, and the chemical kinetics of the regeneration reaction are unfavorable for many prior art materials.
Accordingly, there is a need for a material which is capable of rapidly removing sulfur compounds from a feedstock. The material should also have a high specific capacity for the removal of sulfur compounds, and it is further desirable that the material be capable of being easily regenerated for reuse. As will be explained hereinbelow, the present invention provides a composite material which comprises a ceramic matrix having a nanoscale dispersal of a reactive sulfur-absorbing metal therein. The material of the present invention is stable in use, capable of absorbing large amounts of sulfur, and capable of being easily regenerated. These and other advantages of the present invention will be apparent from the drawings, discussion, and description hereinbelow.